I'm sorry this has made you feel bad. I'm not worried about the girls at all, they will do whatever silly thing they will do.
Certainly have no concern about your ex, he is just, as he is.
I think perhaps the shock also comes, perhaps, somewhat, for getting a look at the REAL him.
For me and this is just what I would do. I would stop her visiting his place immediately. He is having strangers (to you) over at his place, tracking in germs from all their travels. This puts your Daughter at huge risk for picking up the virus.
Whether he is choosing this risky behaviour because he is an out of touch drunk or because he lacks the maturity and integrity to keep you Daughter safe is a bit irrelevant right now I suppose.
As for you, this will pass. Your hurt will pass although right now it is probably a bit overwhelming. Keep putting one foot in front of the another, try to put your focus elsewhere whenever possible, you will get past this.
Hang in there, post as much as you need to, take care of yourself.